Cupric cellulose impregnated and coated fabric



Patented Jan. 9, 1940 UNITED STATES FATEN'E CUPRIC CELLULOSE IMPREGNATEDAND COATED FABRIC Clarence a. White, Moutclair, N. a.

Serial No. 125,033

No Drawing. .Applieation February 1937,

7 Claims.

This invention relates, generally, to cuprammonium coatings, and theinvention has reference, more particularly, to a novel fabric emplayinga cuprammonium coating that is so applied to the fabric as to penetratethe same in anchoring relation, whereby the external coating is firmlyadhered to the fabric.

Heretofore, coatings of this type have been applied to fabrics in apurely superficial manv ner by passing the fabric to be coated through acellulose solvent bath of ammoniacal cupric oxide having the generalformula of (Cu(NI-I3) 4) (OH) 2,

7 the general effect of which passage through the bath is the solutionof a portion of the surface of the passing fabric in the ammoniacalcupric oxide with the formation of an extremely viscous solution ofcupric tetrammonium cupric cellu- Io lose of a composition(Cm-I-lmO-lO-Cu) (Cu(NH3)4) which, because of its viscosity, the factthat it dissolves the cellulose with which it comes into contact, andbecause ordinary grey goods are exceedingly repellant due to thepresence of natural waxes, fails to enter the texture of the fabric andremains strictly on its surface, thereby forming merely a superficialcoating which is quickly worn off in use. This surface coating isgenerally coagulated either by heat or by passing through acid baths,whereby the cellulose content is precipitated or coagulated asregenerated cellulose, the ammonia being removed, whereby the remainingsurface deposit is caused to assume a very lustrous appearance that isof a greenish blue color due to the copper content, the film or coatingin the finished article consisting of regenerated cellulose which,chemically, is C12H20010+Cl1(OH)2, the latter providing the color.

Owing to the thinness of the coating and the necessity of securingsufiicient lustre and density of pigmentation, it is usually necessaryto r pass the fabric three or more times through the bath of ammoniacalcupric oxide, drying and heating after each passage. The necessity ofthese multiple passages adds greatly to the expense of manufacturebecause of the excessive use of ammonia, the slowing down of productionand the additional labor required, while at the same time the strengthof. the goods in both warp and filling threads is reduced, becauseanappreciable portion of the-cellulose thereof is '66 dissolved awayfrom the surface of the fabric.

The three or more passages through the bath also have the effect ofcausing a serious shrinkage in the width of the goods, which shrinkagefrequently amounts to as much as 10% of the original width of thefabric. When cloth as thus 5 prepared is used for filtration purposes,it has been found that the coating, being purely superficial, is readilydissolved in the presence of dilute acids, leaving the coating in aflaccid, porous condition which will not stand up in use. 19 Also, suchcoated fabrics, as heretofore produced, are objectionable inasmuch asthey are subject to mildew in their interiors, where the surface coatingdoes not penetrate.

The principal object of the present invenu tion is to provide a novelcupric cellulose im-' pregnated and coated fabric which is so fabricatedas to provide a body of cupric cellulose within the body of the fabric,the function of which body is to anchor and make permanent the exterioror surface coating of cupric cellulose, whereby the novel fabric of thisinvention has its coating extending practically throughout and integralwith the fabric itself and therefore will not flake off or wear off,thereby greatly 35 proionging' the life of thefabric in use, whilepossessing all the valued properties of the typical superficialcuprammonium coating;

Another object of the present invention lies in the method of making anovel impregnated and coated fabric of the above character, which methodcomprises depositing within and throughout the fabric body a salt ofcopper and then insolubilizing such salt in a form which will produce,when brought into contact with a solution 35 of ammonia, the ammoniacaloxide of copper or cuprammonium solution, which latter dissolves some ofthe internal cellulose and then is regenerated as cupric cellulosewithin the fabric and on the surface thereof, the surface coating 40being integral with and bound to the interior impregnation, therebyproviding a durable and permanently coated fabric.

Another object of the present invention is to provide a novel method ofproducing the im- 46 pregnated and coated fabric of this invention,which method lessens the cost of production by eliminating one or moreof the usual passages of the fabric through the ammoniacal cupric oxidebath, and at the same time greatly reducing the shrinkage of the fabric,heretofore amounting to about 10% of the width thereof. Still anotherobject of the present invention lies in the provision of a novelimpregnated and Qated fabric of the above character'that is II strongerthan fabrics heretofore produced, of the same weight, owing to thediminution in the solvent action of the impregnating solution, anincrease in-copper pigmentation due to the penetration of the fabric bythe cupric cellulose, and a substantial increase in the mildewresistance of the fabric due to the penetration thereof by the surfacecoating, and a substantial increase in the resistance of the fabric toweathering, and especially to the action of atmospheric acids.

Other objects and advantages will become apparent from the accompanyingspecification.

In carrying out the invention, the fabric to be impregnated and coatedis first thoroughly impregnated by passing the same through a bath of asoluble salt of copper, such as copper acetate, chloride, sulphate,etc., the cloth. being passed between heavy rubber squeeze rollers whichforce the. copper solution into the fabric. At times it is necessary torepeat this operation in order to secure sufficient impregnation,inasmuch as the fabric contains natural waxes which offer resistancetothe impregnation.

After the fabrichas been thoroughly impregnated, it is dried and passedthrough a hot bath of sodium hydroxide, which converts the containedcopper salts into copper hydroxide. If the impregnation operation iscarefully controlled and the fabric is thereafter thoroughly driedbefore treating with the sodium hydroxide, the cloth will be thoroughlyimpregnated with the copper hydroxide in an amorphous or 'extremely finegrain crystal form which adheres very firmly to the fibers and will notpowder off. This treatment of the fabric with sodium hydroxide alsoserves to remove the major portion of the natural waxes contained withinthe fabric, thereby overcoming the normal resistance to impregnationoffered by the fabric. The fabric is then washed and preferably dried.

The fabric is now passed through a solution of ammoniacal cupric oxideindicated by the formula Cu(NHs)4(OH)2, there being an excess of ammoniain the solution, whereby a thorough penetration of the fabric isobtained. The penetrating excess ammonia of the ammoniacal cupric oxidesolution reacts with the copper hydroxide as follows:

producing ammoniacal cupric oxide solution which reacts with theinternal cellulose of the fabric as follows:

Thus cupric tetrammonium cupric cellulose throughout the body of thefabric is produced, this compound being in the form of a gelatinous,viscous coating and impregnation.

The fabric is then passed through rubber rolls or doctor blades whichscrape off the excess and also press this compound firmly into thefabric.

the ammoniacal cupric oxide within the fabric being combined with aportion of the cellulose thereof to form cupric tetrammonium cupriccellulose within the bodyof the fabric, and this impregnated materialcoalesces with the surface material of the same nature, thereby firmlyanchoring the cuprammonium surface coating with the impregnated materialof the fabric.

The fabric is then passed through a hot flue or overheated cans, therebydriving off the ammonia and producing a fabric with a flexible, glossy"coating that extends throughout the fabric as an impregnation thereof,the reaction which takes place being understood as follows:

As a specific example of the method of this invention,'the strength ofthe copper salt bath used, 1. e., the acetate of copper, wouldordinarily be within the limits of from 6 to 10 ounces of acetate ofcopper to a gallon of water. The bath may be either cold or hot, butpreferably about F., and the impregnation is effected by passing thecloth to be impregnated through this bath, whence it goes between heavysqueeze rolls of rubber, or equivalent, which squeeze out the excess andalso force in the liquid of the bath to the interior of the fabric bymechanical pressure. It is sometimes necessary to repeat the passagethrough the bath and the squeezing through the rolls to achieve aneffective impregnation. The goods are then thoroughly dried by passingover cans or through heated flues, or an equivalent drying process. Thedrying may be effected at any temperature from room temperature to ormore, but should be thorough.

The dried fabric is now passed through a solution of sodium hydroxide,the strength being about five to seven ounces of sodium hydroxide to thegallon of water, which strength is increased as the strength of thecopper impregnation rises. This solution is used preferably hot. Thefabric is passed through the sodium hydroxide bath and between squeezerolls which remove excess liquid, and then passes to boxes of waterwhere sodium hydroxide liquor is removed by washing. The thoroughlywashed fabric is now thoroughly dried by appropriate drying means. Thecaustic soda treatment insolubilizes the copper as copper hydroxide, andat the same time, by removal of the natural waxes from the fabric,overcomes the natural resistance of the latter to the absorption ofliquids, and the fabric is now relatively absorbent.

The dried fabric, now thoroughly impregnated with copper hydroxide in astate of fine division, is passed through a cold (40 degrees, F. orlower) solution of ammoniacal cupric oxide, then squeezed to removeexcess of cupric tetrammonium cupric cellulose and force ammoniasolution and the cupric tetrammonium cupric cellulose cdagulated and thecellulose thus regenerated, as hereinbefore described.

It will be understood that the invention is not limited solely to theuse of acetates of copper,

since any of the salts of copper which are precipi-.

tated as hydroxides by caustic soda may be used. Instead ofprecipitating a hydroxide by means of caustic, the copper may beprecipitated by means of a carbonate of an alkali metal, producingcopper basic carbonate, by a chromate of an' alkali metal, producingbasic copper chromate, and by sodium sulphide, producing cupric sul-'means w phide, all of which compounds, and some others, are suitable forthe production, in combination with ammonia, of a serviceablecellulosesolvent terfering with its operation. Such metals are iron, manganese,nickel, cobalt, vanadium, all of which are capable of forming sulphidesin the wet way when subjected to the action of alkali metal sulphides.They can be described .as metalsthat are capable of forming sulphides inthe wet way. Such additions seem to be inert in most other'respects andexercise no protective.

influence in connection with either coating or fabric.

Also, instead of using copper acetate alone, I may use a rare earthacetate along with the copper acetate, as given in the followingexample:

Example #2.-The. fabric is impregnated in a bath, the composition ofwhich is as follows: Copper acetate, 6- ounces tothe gallonof water;rare earth acetate,'6 ounces to the gallon of water.

The modusoperandi. of impregnation has already been described.

The impregnated fabric is thoroughly dried. The dried fabric is passedthrough a hot solution of sodium hydroxide, about 8 ounces to thegallon.

The goods are thoroughly Washed and dried. The fabric, washed and dried,is then passed through a cold solution of ammoniacal cupric houpricoxide, squeeze off. excess cupric tetram-' oxide, and the excesssqueezed off .by passage through the rolls.

The coated fabric is now dried under'heat t volatilize and remove allammoniapresent, leaving a glazed surface colored by contained cupric'hydro'xide.

monium cupric cellulose, and dry under heat. The passage through theammoniacal cupric oxide may be repeated, if deemed necessary.

Example #4.--Th fabric is impregnated with the following solution:Copper acetate, 6 ounces to the gallon of water; rare earth acetate, 6

ounces to the gallon of water.

I The impregnated fabric, after drying thorpughly, is passed through asolution of sulphide of sodium, 8 ounces to the gallonof water. Thefabric is then thoroughly washed and dried. Pass through the coldsolution of ammoniacal cupric oxide, squeeze off excess of cuprictetrammonium cupric cellulose thus formed, and dry under heat. Ifrequired, the passage through the ammoniacal cupric oxide mayberepeated.

Example #5.-The fabric is impregnated with the following solution:Copper acetate, 6 ounces to the gallon of water.

The impregnated fabric, after thorough drying,

is passed through a solution of sodium chromate.

or bichromate. The fabric is then thoroughly washed and dried. Passthrough a cold solution of ammoniacal cupric oxide, squeeze oh theexcess of cupric tetrammonium cupric cellulose, and

dry with heat to volatilize the ammonia. The passage through theammoniacal cupric oxide solution may be repeated, if considerednecessary. a

Example #6.The fabric is impregnated-with the following solution: Copperacetate, 6 ounces to the gallon of water.

The impregnated fabric,- after thorough drying,

is passed through a bath of sodium hydroxide. to

It is then washed and dried thoroughly. Pass through a cold solution ofammoniacal cupric o-xlde,. squeeze, and then pass through a dilutesolution of acid, e. g., sulphuric acid, after winchwash and dry. Thefabric will be coated with a w film of regenerated cellulose, but therewill be no copper content in the goods. The internally developed coatingwill also consist of plain, regenerated cellulose without copper.

The novel fabric of the present invention, thus 4219 produced, has adeep color pigmentation due to the impregnation of the fabric with thecoating thereof, the interiorly contained copper compounds adding to thecoloring effect of the surface compounds, thereby giving ample depth of85 shade, which heretofore has been very difficult.

At the same time, the interiorly contained copper compound insurescomplete mildew resistance and permanency of color in conditions ofweather exposure that would quickly remove the copper 80 contained inordinary cupric cellulose films.

Since ample depth of color is obtained in the present invention withoutmultiple passages through the expensive solution of ammoniacal cupricoxide, not only are considerable labor and, 35

raw material saved, but production is greatly sp'eed'ed up and theshrinkage of the fabric is reduced.

The surface coating has a lustrous, continuous and pleasing appearancethat is firm and yet? elastic and well able -to withstand the abra'dingeffect of scrapers used in connection with filtration processes, therebyespecially adapting the novel fabric of this invention for filtrationuse.

Although this invention has been described in 6 connection with theimpregnation and coating of fabrics, it is to be understood that thesame is equally applicable to the impregnation and coating of-yarns,etc.

By therare earth metals mentioned in the 50 above examples, I intend toinclude zirconium and thorium. V

What .is claimed is:

1. The steps in the method of fabricating an impregnated and coatedcellulosic fiber material, 55

comprising thoroughly impregnating the cellulosic fiber material with asoluble copper salt, dry ing theimpregnated material, passing thematerial through an alkali insolubilizing bath, washing and drying themateriaLand passing the 0 dried material through a solution ofammoniacal cupric oxide.

2. The steps in the method of producing an impregnated and coatedcellulose fabric, compris= ing passing the fabric. through a copper saltsolu- 5 solution of anunonia'cal cupric oxide and be- 7 tween squeezerollers to eliminate excess and to I force the solution into thefabrics, whereby cup- .ric tetrammonium cupric cellulose is formedthroughout and on the. surfaces of the fabric body.

3. The method of fabricating an impregnated and coated cellulosicfabric, comprising impregnating a fabric with a soluble salt of copper,insolubilizing such salt by passing the impregnated fabric through analkali insolubilizing bath, impregnating the fabric with ammoniacaloxide of copper to produce cupric tetrammonium cupric cellulosedispersed throughout and covering the surface of the fabric, and thenheating the thusly treated fabric to produce the finished impregnatedand coated fabric having regenerated cellulose dispersed throughout thebody thereof and a surface coating of the same material formed integraltherewith.

4. The method of fabricating a cupric cellulose impregnated and coatedcellulosic fabric, comprising passing a fabric through a copper saltsolution while forcing the solution into the fabric, drying the fabric,passing the dried fabric through a hot bath of sodium hydroxide forconverting the impregnated copper salt to copper hydroxide, washing anddrying the fabric, passing the fabric through a solution of ammoniacalcupric oxide containing an excess of ammonia to produce cuprictetrammonium cupric cellulose throughout and on the surfaces of thefabric, and

then applying heat to the fabric to drive-off ammonia to produce thefinished fabric having a flexible, glossy coating on the surfacesthereof, the material of which coating penetrates throughout the body ofthe fabric.

5. The method of fabricating an impregnated and coated cellulosicfabric, comprising impregnating a cellulosic fabric with a soluble saltof copper, drying the impregnated fabric, passing the dried fabricthrough a bath of an alkali compound for converting the copper into awater insoluble form, washing and drying the fabric, passing the driedfabric through a cellulosesol- "vent solution of ammoniacal cupric oxideto form a substantially continuous coating of cupric tetrammonium cupriccellulose, at the same time liberating ammonia, forcing this ammoniainto the fabric, whereby this ammonia combines with the copper compounddeposited within the material to form ammoniacal cupric oxide. whichlatter material reacts with the interior cellulose content of the fabricto form cupric tetrammonium cupric cellulose within the fabric, and thenheating the thusly treated cellulosic textile fabric to produce thefinished impregnated and coated fabric having cupriocellulose dispersedthroughout the body thereof and a surface coating of the same materialformed integrally therewith.

6. The steps in the method of fabricating an impregnated and coatedcellulosic fibrous material possessing a substantially continuous lus-'trons coating of cupric cellulose, comprising ,thoroughly impregnatingthe cellulosic fibrous material with a soluble copper salt, drying thethus impregnated material, passing the dried material through a bath ofan alkali chromate or dichromte capable of converting the copper into aninsoluble chromate of copper, washing and drying the material, passingthe washed and dried cellulosic impregnated material through a cellulosesolvent solution of ammoniacal cupric oxide to form a coating of cuprictetrammonium cupric cellulose on the surface of the material, at thesame time liberating ammonia from the solution of ammoniacal cupricoxide, forcing this ammonia together with any excess ammonia presentinto the interior of the material, where it combines with the copperimpregnation and forms ammoniacal cupric oxide, which latter combineswith a portion of the cellulose of the material itself and forms cuprictetrammonium cupric cellulose in situ within the fabric, and thenheating the thusly treated material to change the cupric tetrammoniumcupric cellulose into cupric cellulose, at the same time driving off theammonia, thereby producing the finished impregnated and coated materialhaving cupric cellulose dispersed throughout the body thereof and asurface coating of the same material formed integrally therewith.

7. The steps in the method of fabricating an impregnated and coatedcellulosic fabric possessing a substantially continuous coating ofregenerated cellulose, comprising thoroughly impregnating cellulosicfabric with a soluble copper salt, drying the thus impregnated material,passing thedried fabric through an insolubilizing bath of an alkalicompound capable of converting the contained copper into a waterinsoluble form, washing and drying the fabric thus treated, and passingthe washed and dried fabric through 'a cellulose solvent solution ofammoniacal cupric oxide to form a coating of cupric tetrammonium cupriccellulose on the surface of the textile material under treatment, at thesame time liberating ammonia from the ammoniacal cupric oxide, forcingthis liberated ammonia together with any excess ammonia present in theammoniacal cupric oxide into the internal portions of the fabric, thereto react with the contained copper resulting from the impregnation toform ammoniacal cupric oxide solution, which latter combines immediatelywith a portion of the cellulose of the fabric to form cuprictetrammonium cupric cellulose within the fabric, and passing the thuslyprocessed fabric through a dilute acid solution to dissolve and removethe contained copper, washing the thusly treated fabric thoroughly inwater to remove all traces of acids, arid drying to produce a finishedimpregnated and coated fabric having regenerated cellulose dispersedthroughout thereof, and a surface coating of regenerated celluloseunited integrally with the dispersed regenerated cellulose within thebody of the fabric.

' CLARENCE B. WHITE.

